Recent advances and applications of microspheres and nanoparticles in transarterial chemoembolization for hepatocellular carcinoma

Fusible and Radiopaque Microspheres for Embolization

In this work, fusible microspheres loaded with radiopaque agents as an embolic agent for transcatheter arterial embolization (TAE) are developed. A poly(ethylene glycol) (PEG) and poly(ε-caprolactone) (PCL) multi-block copolymer basing polyurethane (PCEU) is synthesized and fabricated into blank microspheres (BMs). The microspheres are elastic in compression test. A clinical contrast agent lipiodol is encapsulated in the microspheres to receive fusible radiopaque microspheres (FRMs). The sizes of FRMs are uniform and range from 142.2 to 343.1 µm. The encapsulated lipiodol acts as the plasticizer to reduce the melting temperature point (Tm) of PECU microspheres, thus, leading to the fusion of microspheres to exhibit efficient embolization in vivo. The performance of FRMs is carried out on a rabbit ear embolization model. Serious ischemic necrosis is observed and the radiopacity of FRMs sustains much longer time than that of commercial contrast agent Loversol in vivo. The fusible and radiopaque microsphere is promising to be developed as an exciting embolic agent.

Functional hydrogels for hepatocellular carcinoma: therapy, imaging, and in vitro model

Hepatocellular carcinoma (HCC) is among the most common malignancies worldwide and is characterized by high rates of morbidity and mortality, posing a serious threat to human health. Interventional embolization therapy is the main treatment against middle- and late-stage liver cancer, but its efficacy is limited by the performance of embolism, hence the new embolic materials have provided hope to the inoperable patients. Especially, hydrogel materials with high embolization strength, appropriate viscosity, reliable security and multifunctionality are widely used as embolic materials, and can improve the efficacy of interventional therapy. In this review, we have described the status of research on hydrogels and challenges in the field of HCC therapy. First, various preparation methods of hydrogels through different cross-linking methods are introduced, then the functions of hydrogels related to HCC are summarized, including different HCC therapies, various imaging techniques, in vitro 3D models, and the shortcomings and prospects of the proposed applications are discussed in relation to HCC. We hope that this review is informative for readers interested in multifunctional hydrogels and will help researchers develop more novel embolic materials for interventional therapy of HCC.

Unleashing the potential: transarterial chemoembolization combined with intra-arterial infusion of bevacizumab for unresectable hepatocellular carcinoma

BACKGROUND

The purpose of this study is to compare the efficacy and safety of transarterial chemoembolization (TACE) alone with transarterial chemoembolization combined with the arterial infusion of bevacizumab (TACE + Bev) in patients with unresectable hepatocellular carcinoma (uHCC).

METHODS

A retrospective analysis was conducted on 446 uHCC patients treated with TACE or TACE + Bev between January 2021 and March 2023. The study evaluated objective response rate (ORR), disease control rate (DCR), progression-free survival (PFS), overall survival (OS), and adverse events in both treatment groups.

RESULTS

Finally, the TACE group comprised 295 patients, and the TACE + Bev group comprised 151 patients. Patients in the TACE + Bev group exhibited significantly prolonged median PFS (7.9 months vs. 10.3 months, P = 0.013) and median OS (16.1 months vs. 21.4 months, P = 0.041), improved ORR (26.8% vs. 37.7%, P = 0.017) and DCR (71.5% vs. 80.8%, P = 0.033) compared to the TACE group. Multifactorial Cox analysis identified alpha-fetoprotein (AFP) > 400 ng/ml as an independent prognostic factor for PFS and OS. Meanwhile, portal vein cancer thrombosis and distant metastasis are poor prognostic factors for OS. The overall incidence of adverse events was similar between the two groups.

CONCLUSION

In comparison with the TACE group, the TACE + Bev group demonstrated efficacy in improving outcomes for patients with uHCC with a manageable safety profile.

Current research status and development prospects of embolic microspheres containing biological macromolecules and others

Transcatheter arterial embolization (TACE) has been used in the treatment of malignant tumors, sudden hemorrhage, uterine fibroids, and other diseases, and with advances in imaging techniques and devices, materials science, and drug release technology, more and more embolic agents that are drug-carrying, self-imaging, or have multiple functions are being developed. Microspheres provide safer and more effective therapeutic results as embolic agents, with their unique spherical appearance and good embolic properties. Embolic microspheres are the key to arterial embolization, blocking blood flow and nutrient supply to the tumor target. This review summarizes some of the currently published embolic microspheres, classifies embolic microspheres according to matrix, and summarizes the characteristics of the microsphere materials, the current status of research, directions, and the value of existing and potential applications. It provides a direction to promote the development of embolic microspheres towards multifunctionalization, and provides a reference to promote the research and application of embolic microspheres in the treatment of tumors.

Preparation of cassava starch-gelatin yolk-shell microspheres by water-in-water emulsion method

This paper reports the preparation and characterization of gelatin-cassava starch microspheres using the water-in-water emulsion technique. The effects of different weight ratios (10: 0, 9: 1, 8: 2, 7: 3, 6: 4, 5: 5) of starch to gelatin on the morphology, structure, thermal properties, and stability of microspheres were investigated. The morphology results showed that most microspheres had spherical shapes and smooth surfaces. When the weight ratio of starch to gelatin was 5: 5, the prepared microspheres formed a stable yolk-shell structure. The swelling capacity of the microspheres increased with the proportion of gelatin, up to 682.3 %. The gelatin and starch in the microspheres were compatible but not miscible. Compared with the native starch, the crystalline structure of microspheres changed from A-type to a mixture of B-type and V-type, and the relative crystallinity decreased. Differential scanning calorimetry results showed that the melting of microspheres involved both gelatin dissolution and starch gelatinization. Due to the formation of composite microspheres, the starch content decreased, and the release of reducing sugars from the microspheres upon hydrolysis was reduced. The gelatin-cassava starch microspheres are simple to prepare, biocompatible, and can be used as a potential material for microencapsulation.

Radioiodine-131-Labeled Theranostic Nanoparticles for Transarterial Radioembolization and Chemoembolization Combination Therapy of VX2 Liver Tumor

In interventional treatment, materials are administered into the blood supply artery and directly delivered to tumors, offering proper scenarios for nanomedicine potential clinical applications. Transarterial chemoembolization (TACE) and transarterial radioembolization (TARE) are effective treatment methods for hepatocellular carcinoma (HCC), but postoperative residual tumor may result in intrahepatic recurrence and distant metastasis. The combination therapy of TACE and TARE based on multifunctional nanoparticles (NPs) is expected to overcome the drug resistance in hypoxic tumors and improve the therapeutic effect. Herein, BaGdF5 NPs are synthesized and then coated with polydopamine (PDA), conjugated with the chemotherapeutic drug cis-diamminedichloride platinum (CDDP), radio-labeled with therapeutic radionuclide 131 I, yielding 131 I-BaGdF5 @PDA-CDDP NPs. The in vitro anti-cancer effects of 131 I-BaGdF5 @PDA-CDDP NPs are confirmed using CCK-8 and γ-H2AX assays in Huh7 cells. Mixed with Lipiodol, 131 I-BaGdF5 @PDA-CDDP NPs are injected into the hepatic artery via a microcatheter to realize the TACE and TARE combination therapy in a rabbit VX2 liver tumor model. The results indicate that glucose metabolism is clearly decreased based on 18 F-FDG PET imaging and the apoptosis of tumor cells is increased. Furthermore, 131 I and BaGdF5 NPs can be used for SPECT imaging and CT/MR imaging respectively, facilitating real-time monitoring of the in vivo biodistribution of 131 I-BaGdF5 @PDA-CDDP NPs.

Design of an imaging magnetic microsphere based on photopolymerization for magnetic hyperthermia in tumor therapy

Magnetic hyperthermia therapy has been widely used in the nonsurgical treatment of patients with advanced stage cancers that cannot be treated by surgery. It is minimally invasive, precise, and highly efficient and has a good curative effect. In this paper, a magnetic microsphere with Fe3O4 was prepared for thermal therapy and imaging based on a photoinitiated suspension polymerization method from biallelic monomers. The preparation method clearly minimized the degradative chain transfer of allyl polymerization reactions. The microspheres were characterized by microscope observation, spectral analysis, thermal analysis, and magnetic testing. The magnetothermal effect was detected by an infrared thermal imager in vitro and in vivo under a high-frequency alternating magnetic field (AMF). The antitumor effect was verified by testing the viability of H22 cells and observing a tumor-bearing mouse model under high-frequency AMF. Biocompatibility was evaluated by cell viability assay, tissue section observation, and blood biochemical analysis. The imaging capacity was tested by X-ray, MRI, and CT imaging experiments. The results show that the product has good dispersibility, thermal stability, superparamagnetism, and biocompatibility. Under the action of an AMF, the magnetic hyperthermia effect in tumor-bearing mice was better, and an antitumor effect could be achieved.

Multifunctional nanoplatforms application in the transcatheter chemoembolization against hepatocellular carcinoma

Hepatocellular carcinoma (HCC) has the sixth-highest new incidence and fourth-highest mortality worldwide. Transarterial chemoembolization (TACE) is one of the primary treatment strategies for unresectable HCC. However, the therapeutic effect is still unsatisfactory due to the insufficient distribution of antineoplastic drugs in tumor tissues and the worsened post-embolization tumor microenvironment (TME, e.g., hypoxia and reduced pH). Recently, using nanomaterials as a drug delivery platform for TACE therapy of HCC has been a research hotspot. With the development of nanotechnology, multifunctional nanoplatforms have been developed to embolize the tumor vasculature, creating conditions for improving the distribution and bioavailability of drugs in tumor tissues. Currently, the researchers are focusing on functionalizing nanomaterials to achieve high drug loading efficacy, thorough vascular embolization, tumor targeting, controlled sustained release of drugs, and real-time imaging in the TACE process to facilitate precise embolization and enable therapeutic procedures follow-up imaging of tumor lesions. Herein, we summarized the recent advances and applications of functionalized nanomaterials based on TACE against HCC, believing that developing these functionalized nanoplatforms may be a promising approach for improving the TACE therapeutic effect of HCC.

Material characterization of GPX®: A versatile in situ solidifying embolic platform technology

Endovascular embolization is a minimally invasive procedure during which blood flow to targeted tissues is selectively occluded. The list of clinical indications for embolization continues to expand. Liquid embolic agents are injectable compositions that transition into a solid or semi-solid form when introduced into blood vessels. The mechanism that triggers the liquid-to-solid transition is a key distinguishing feature of liquid embolic agents. GPX is a waterborne liquid embolic agent comprising oppositely charged polyelectrolytes: polyguanidinum and inorganic polyphoshate. In situ solidification is driven by electrostatic condensation of the polyelectrolytes, triggered by ionic strength differentials. We report in vitro characterization of the material properties of GPX, it is in vivo effectiveness in acute animal studies, and its potential for chemoembolization. The viscosity of GPX can be varied over a wide range by adjusting the polyguanidinium MW and/or concentration. Formulation of GPX with either tantalum microparticles (30 wt%) or iodinated radiocontrast agents (300 mgI ml^-1) did not significantly change the flow behavior of GPX; the viscosity was independent of shear rate and remained within a clinically practical range (80-160 cP). Formulation of GPX with doxorubicin substantially increased viscosity at low shear rates and resulted in a power law dependence on shear rate. High contrast and effective vascular occlusion were demonstrated in both swine kidneys and rete mirabile. Contrast from iodinated compounds was temporary, dissipating within hours. The doxorubicin in vitro release profile was linear over 90 days. The results demonstrate that GPX is a versatile liquid embolic platform that can be formulated with a wide range of viscosities injectable at clinically practical flow rates, with either transient or permanent contrast, and that can provide prolonged zero-order delivery of doxorubicin to embolized tissues.

Hybrid Polydimethylsiloxane (PDMS) Incorporated Thermogelling System for Effective Liver Cancer Treatment

For the delivery of anticancer drugs, an injectable in situ hydrogel with thermal responsiveness and prolonged drug release capabilities shows considerable potential. Here, we present a series of thermosensitive in situ hydrogels that serve as drug delivery systems for the treatment of liver cancer. These hydrogels were created by utilizing the polydimethylsiloxane (PDMS) oligomer, polyethylene glycol (PEG) and polypropylene glycol (PPG)'s chemical cross-linking capabilities. Doxorubicin (DOX) was encapsulated in a hydrogel with a hydrophobic core and hydrophilic shell to enhance DOX solubility. Studies into the behavior of in situ produced hydrogels at the microscopic and macroscopic levels revealed that the copolymer solution exhibits a progressive shift from sol to gel as the temperature rises. The hydrogels' chemical composition, thermal properties, rheological characteristics, gelation period, and DOX release behavior were all reported. Subcutaneous injection in mice was used to confirm the injectability. Through the in vitro release of DOX in a PBS solution that mimics the tumor microenvironment, the hydrogel's sustained drug release behavior was confirmed. Additionally, using human hepatocellular hepatoma, the anticancer efficacy of thermogel (DEP-2@DOX) was assessed (HepG2). The carrier polymer material DEP-2 was tested for cytotoxicity using HepG2 cells and its excellent cytocompatibility was confirmed. In conclusion, these thermally responsive injectable hydrogels are prominent potential candidates as drug delivery vehicles for the treatment of hepatocellular carcinoma.

CT/MR detectable magnetic microspheres for self-regulating temperature hyperthermia and transcatheter arterial chemoembolization

The embolic microspheres containing magnetic nanoparticles and anti-tumor drugs have been proposed for transcatheter arterial chemoembolization (TACE). However, this technique still suffers the poor control of hyperthermia temperature and drug release behavior. Herein, the magnetic microspheres based on low Curie temperature superparamagnetic iron oxide nanoparticles are developed by emulsification cross-linking of gelatin, genipin, and sodium alginate. The magnetic microspheres can self-regulate the hyperthermia temperature at around 50°C, un-necessitating any temperature control facilities. The magnetic microspheres can load doxorubicin hydrochloride and the loaded drug can be released in a controllable way by using an alternating magnetic field. Cytocompatibility and hemolysis evaluations confirm the non-cytotoxicity and negligible hemolysis of magnetic microspheres. The embolization model on rabbit auricular artery demonstrates that the magnetic microspheres can occlude the targeted blood vessel and are visualized under CT/MR imaging. All these findings suggest that the prepared magnetic microspheres could be used as the embolic agent in TACE. STATEMENT OF SIGNIFICANCE: The existing magnetic embolic microspheres suffer the poor control of hyperthermia temperature and drug release behavior in TACE. In this work, we developed the magnetic embolic microspheres based on superparamagnetic iron oxide nanoparticles with a low Curie temperature. Upon the application of alternating magnetic field, the embolic microspheres can self-regulate the hyperthermia temperature at around 50°C and the drug loaded in the microspheres can be released in a somewhat controllable manner. The embolic microspheres are also detectable to both CT and MR. These characteristics enable the developed microspheres to simultaneously realize self-regulating temperature hyperthermia, on-demand drug release, embolism, and CT/MR imaging.

Multimodal imaging of nano-assembled microspheres loaded with doxorubicin and Cisplatin for liver tumor therapy

Currently, clinically available drug-loaded embolic microspheres have some shortcomings, such as being invisible with standard medical imaging modalities and only being able to carry positively charged drugs. The visualization of drug-loaded microspheres is very important for real-time monitoring of embolic position to improve the therapeutic effect. Meanwhile, the visualization of microspheres can enable postoperative reexamination, which is helpful for evaluating the embolization area and guiding the subsequent treatment. In addition, microspheres capable of loading different charged drugs can increase the choice of chemotherapeutic drugs and provide more possibilities for treatment. Therefore, it is of great importance to explore drug-loaded microspheres capable of multimodal imaging and loading drugs with different charges for transarterial chemoembolization (TACE) treatment of liver tumors. In our study, we designed a kind of nano-assembled microspheres (NAMs) that can realize computer X-ray tomography (CT)/magnetic resonance imaging (MRI)/Raman multimodal imaging, be loaded with positively and negatively charged drugs and test their imaging ability, drug loading and biological safety. The microspheres have strong attenuation performance for CT, high T₂ relaxation for MRI and good sensitivity for surface enhanced Raman spectroscopy (SERS). At the same time, our microspheres can also load the positively charged drug, doxorubicin (DOX), and negatively charged drug Cisplatin. One gram of NAMs can hold 168 mg DOX or 126 mg Cisplatin, which has good drug loading and sustained-release capacity. Cell experiments also showed that the nano-assembled microspheres had good biocompatibility. Therefore, as multimodal developed drug loaded microspheres, nano assembled microspheres have great potential in TACE treatment of liver cancer.

Iridium Complex-Loaded Sorafenib Nanocomposites for Synergistic Chemo-photodynamic Therapy of Hepatocellular Carcinoma

Although sorafenib, a multi-kinase inhibitor, has provided noteworthy benefits in patients with hepatocellular carcinoma (HCC), the inevitable side effects, narrow therapeutic window, and low bioavailability seriously affect its clinical application. To be clinically distinctive, innovative drugs must meet the needs of reaching tumor tissues and cause limited side effects to normal organs and tissues. Recently, photodynamic therapy, utilizing a combination of a photosensitizer and light irradiation, was selectively accumulated at the tumor site and taken up effectively via inducing apoptosis or necrosis of cancer cells. In this study, a nano-chemo-phototherapy drug was fabricated to compose an iridium-based photosensitizer combined with sorafenib (IPS) via a self-assembly process. Compared to the free iridium photosensitizer or sorafenib, the IPS exhibited significantly improved therapeutic efficacy against tumor cells because of the increased cellular uptake and the subsequent simultaneous release of sorafenib and generation of reactive oxygen species production upon 532 nm laser irradiation. To evaluate the effect of synergistic treatment, cytotoxicity detection, live/dead staining, cell proliferative and apoptotic assay, and Western blot were performed. The IPS exhibited sufficient biocompatibility by hemolysis and serum biochemical tests. Also, the results suggested that IPS significantly inhibited HCC cell proliferation and promoted cell apoptosis. More importantly, marked anti-tumor growth effects via inhibiting cell proliferation and promoting tumor cell death were observed in an orthotopic xenograft HCC model. Therefore, our newly proposed nanotheranostic agent for combined chemotherapeutic and photodynamic therapy notably improves the therapeutic effect of sorafenib and has the potential to be a new alternative option for HCC treatment.

Emerging Polymer Materials in Trackable Endovascular Embolization and Cell Delivery: From Hype to Hope

Minimally invasive endovascular embolization is a widely used clinical technique used for the occlusion of blood vessels to treat various diseases. Different occlusive agents ranging from gelatin foam to synthetic polymers such as poly(vinyl alcohol) (PVA) have been commercially used for embolization. However, these agents have some drawbacks, such as undesired toxicity and unintended and uncontrolled occlusion. To overcome these issues, several polymer-based embolic systems are under investigation including biocompatible and biodegradable microspheres, gelling liquid embolic with controlled occlusive features, and trackable microspheres with enhanced safety profiles. This review aims to summarize recent advances in current and emerging polymeric materials as embolization agents with varying material architectures. Furthermore, this review also explores the potential of combining injectable embolic agents and cell therapy to achieve more effective embolization with the promise of outstanding results in treating various devastating diseases. Finally, limitations and challenges in developing next-generation multifunctional embolic agents are discussed to promote advancement in this emerging field.